Weston standard cells having resiliently biassing plug means

ABSTRACT

In a Weston standard cell the liquid and semiliquid electrodes are maintained in position by a plug above, and biassed towards, each electrode. Cementing resins are not needed to hold the plugs in position, and contamination of the cell is thereby avoided. The plugs may be biassed by coil springs made from glass.

United States Patent inventor Ruth Friedrichs Hannover, Germany Appl.No. 830,391 Filed June 4, 1969 Patented Nov. 16, 1971 AssigneePyro-Werke Gmbll Ihnnover, Germany Priority Sept. 19, 1968 Germany P 1796 205.9

WESTON STANDARD CELLS HAVING RESILIEN'ILY BIASSING PLUG MEANS 9 Claims,3 Drawing Figs.

US. Cl 136/88 01m 17/114 Field oISearch 136/88,83,

1 1 References Cited UNITED STATES PATENTS 631,044 8/1899 Heinrich136/88 2,189,666 2/1940 Kline 136/164 2,810,007 10/1957 Tucker et a1136/88 2,816,946 12/1957 Vincent 136/88 FOREIGN PATENTS 1,893,152 5/1964Germany Primary Examiner-Winston A. Douglas Assistant Examiner-A.Skapars AttorneyMason, Mason & Albright ABSTRACT: In a Weston standardcell the liquid and semiliquid electrodes are maintained in position bya plug above, and biassed towards, each electrode. Cementing resins arenot needed to hold the plugs in position, and contamination of the cellis thereby avoided. The plugs may be biassed by coil springs made fromglass.

WESTON STANDARD CELLS HAVING RESILIENTLY BIASSING PLUG MEANS BACKGROUNDOF THE INVENTION The invention relates to a standard cell (InternationalWeston Cell) with one semiliquid and one liquid electrode. The positiveelectrode of these cells may consist of chemically pure mercury, whilethe negative electrode may consist of semiliquid cadmium amalgam.

Standard cells are cells required to produce a prescribed electromotiveforce. To this end it is desirable to avoid the use of extraneoussubstances. In addition to this, the progress of the chemical reactionmust not be disturbed, as might occur, for instance, in the event of theliquid and semiliquid electrodes being displaced during transport.

Weston cells known in the present state of the art are unsuitable fortransport. The electrodes may be maintained in position by porcelainplugs or slabs of cork, the porcelain plugs having a rodlike extensionheld in position by being set in cementing resins, but the use of theseextraneous substances shortens the life of the cell.

The purpose of the invention is, by the use of relatively simple meansthat are cheap to produce, to ensure the portability of the standardcell as well as to give it a long life.

BRIEF SUMMARY OF THE INVENTION According to the invention there isprovided a Weston standard cell, comprising one semiliquid and oneliquid electrode which are maintained in position by respective plugmembers, and means for biassing each plug member towards its respectiveelectrode to maintain the latter in position.

Further, according to the invention, there is provided a Weston standardcell, comprising a casing made of inert material, the casing providing achamber for receiving electrolyte and two limbs in which arerespectively situated a liquid electrode and a semiliquid electrode,plug members made of inert material and respectively positioned tomaintain the electrodes in the limbs, and spring means made of inertmaterial and operative to bias the plug members towards the electrodes.

DESCRIPTION OF THE DRAWINGS An example of a standard cell embodying theinvention is explained in greater detail hereunder, in conjunction withthe accompanying purely diagrammatic drawings, in which FIG. I is a sideelevation of the standard cell based on the invention;

FIG. 2 is a side elevation of the insertion used in the standard cell;and

FIG. 3 is a plan corresponding to FIG. 2.

DETAILED DESCRIPTION The standard cell has a casing I, which, in theexample illustrated, is l-I-shaped. The negative electrode 2 consists ofsemiliquid cadmium amalgam, while chemically pure mercury is used forthe positive electrode 3.

Above these two electrodes are plug members, each of which, in theexample illustrated, consists of a pair of discshaped members 4 and 5,separated by a layer of quartz wool 7.

Each of these disc-shaped members 4, 5 has two sealing rims 4a and 4b,5a and 5b respectively, from which the central portion 4c, 5c is setback.

The disc-shaped members 4 and 5 are made of polytetrafluorethylene andare provided with holes 4d (FIG. 3). The design'of the disc membersprovides an elastic seal which is applied under pressure to the innerwall of the cell casing without damage to the cell.

The electrolyte 6 is introduced above the insertions.

Each of the insertions is acted upon by a coil spring 8 made of glass bywhich pressure is exerted and of which the end 80 remote from the plugmembers is fused to the casing I. By the provision of the coil spring 8the plug members are prevented from being displaced.

The assembly of the standard cell will now be described.

To begin with, the two disc-shaped members 4, 5 are inserted under lightpressure into each arm of the casing l, the layers of quartz wool 7being introduced between the pairs of disc-shaped members 4 and 5. Inthis way, the two electrodes 2 and 3 are retained in place.

Before the saturated liquid electrolyte 6 (cadmium sulfate solution, forexample) is introduced the top ends of the arms of the casing l areclosed by melting. This must be done before the liquid is put in, asotherwise the glass cracks. Only a filler stub 1a is left open.

In the course of this melting, the bottom ends of the arms of the casing1 may undergo expansion, which is not desirable. The result of this isthat the disc-shaped polytetrafluorethylene members 4 and 5 may nolonger make such firm contact with the wall in which case the electrodes2 and 3 would no longer be firmly retained.

To prevent displacement of the disc-shaped members 4 and 5, the twoglass coil springs 8 are fused to the casing l in such a way that theyexert pressure on their respective disc-shaped members 4 and 5. Thediameter of the two coil springs 8 is preferably such that they makecontact with the outer third of the disc-shaped members 4 and 5, so thatdisplacement in any direction is reliably prevented.

The contact pressure is made such that the disc-shaped members 4 and 5are forced downwards by up to 2 mm. or so, should they be liftedslightly by percolation of the electrolyte 6.

Finally, the filler stub la is closed by melting.

With an International Weston Cell made in this way, safety in transit isimproved. Experiments with a vibration test bench have clearly confirmedthis.

The embodiment described is merely exemplary of many forms which theinvention can take, and it is intended that the protection be limitedonly to the scope of the appended claims.

What is claimed is:

1. In a Weston standard cell comprising a casing and liquid andsemiliquid electrodes, the improvement comprising slideable plug meansabove the semiliquid and liquid electrodes for maintaining saidelectrodes in position and means for resiliently biassing said plugmeans into contact with said electrodes.

2. A cell according to claim 1, in which said biassing means comprises acoil spring made from glass.

3. A cell according to claim 2, in which the end of said spring remotefrom said slideable plug means is fused to the cell casing.

4. A cell according to claim I, in which the said plug means, comprisestwo superposed disc-shaped members separated by a layer of quartz wool.

5. A cell according to claim 4, in which each of said discshaped memberscomprises a pair of discs in sealed engagement with the cell casing,said discs being separated by a reduced diameter central portion.

6. A cell according to claim I, in which holes are provided in each plugmeans.

7. A cell according to claim 1, in which said plug means are made frompolytetrafluorethylene.

8. A cell according to claim I, in which the casing provides a chambercontaining electrolyte and two limbs opening from the chamber, the plugmeans being respectively positioned to maintain the electrodes in thelimbs.

9. A Weston standard cell including a casing, said casing comprisingmeans defining a chamber containing electrolyte,

a first limb in communication with said chamber and containing a liquidelectrode, and

a second limb in communication with said chamber and containing asemiliquid electrode,

3 4 a slideable plug in each said limb above the electrodes conwithholes, and

tained therein for maintaining the electrodes in position, a respectiveglass coil spring biassing each said plug into said plug comprising,contact with the respective electrode. two superposed disc-shapedmembers separated by a layer of 91 v9 s d sz h e WWW? v ins ramm

2. A cell according to claim 1, in which said biassing means comprises acoil spring made from glass.
 3. A cell according to claim 2, in whichthe end of said spring remote from said slideable plug means is fused tothe cell casing.
 4. A cell according to claim 1, in which the said plugmeans, comprises two superposed disc-shaped members separated by a layerof quartz wool.
 5. A cell according to claim 4, in which each of saiddisc-shaped members comprises a pair of discs in sealed engagement withthe cell casing, said discs being separated by a reduced diametercentral portion.
 6. A cell according to claim 1, in which holes areprovided in each plug means.
 7. A cell according to claim 1, in whichsaid plug means are made from polytetrafluorethylene.
 8. A cellaccording to claim 1, in which the casing provides a chamber containingelectrolyte and two limbs opening from the chamber, the plug means beingrespectively positioned to maintain the electrodes in the limbs.
 9. AWeston standard cell including a casing, said casing comprising meansdefining a chamber containing electrolyte, a first limb in communicationWith said chamber and containing a liquid electrode, and a second limbin communication with said chamber and containing a semiliquidelectrode, a slideable plug in each said limb above the electrodescontained therein for maintaining the electrodes in position, said plugcomprising, two superposed disc-shaped members separated by a layer ofquarts wool, said disc-shaped members being provided with holes, and arespective glass coil spring biassing each said plug into contact withthe respective electrode.